U.S. President Barack Obama has expressed his “sorrow” to Afghan President Hamid Karzai over civilian deaths that U.S.-led airstrikes recently caused in Afghanistan's Helmand province.

White House press secretary Jay Carney says Presidents Obama and Karzai spoke for about an hour via videoconference Wednesday to discuss the state of the war in Afghanistan. Carney said the two leaders noted that most civilian deaths are caused by the Taliban, but would not say whether Mr. Karzai asked Mr. Obama to stop the airstrikes by U.S. Air Force predator drones.

The Afghan leader has been increasingly critical of suspected U.S. air strikes that are often blamed for civilian losses. He said last month that such strikes would no longer be tolerated.

Mr. Obama has said he will begin withdrawing U.S. forces from Afghanistan next month. Carney said no specific date or numbers have been established.

The videoconference took place as the Senate Foreign Relations Committee released a report criticizing Washington's efforts to build a democracy in Afghanistan.

The document said the U.S. has little to show for the nearly $19 billion it has spent and warned further U.S. attempts to rebuild Afghanistan may not survive when foreign troops leave the country in 2014.

Carney said the White House welcomes the report but does not endorse all the conclusions, saying U.S. efforts have broken the Taliban's momentum.

President Obama is considering how many U.S. troops to cut from the estimated 100,000 now in Afghanistan and has said he will make an announcement soon.

Also Wednesday, the nominee for U.S. ambassador to Afghanistan, Ryan Crocker, warned the future of Afghanistan will depend on what happens in neighboring Pakistan.

During testimony before the Senate Foreign Relations Committee, Crocker said progress has been made in Afghanistan, but added the situation will not improve without “a fair measure of success in Pakistan.”

He also warned that terror groups currently based in Pakistan might try to use the planned U.S. military drawdown in Afghanistan as an opportunity to move their bases back across the border.

Crocker said the goal in Afghanistan should be to help create a government that can sustain itself and is “good enough” to prevent the country from again becoming a haven for terrorists.